Archean Eon

The second eon in Earth’s history.

The Archean Eon marked a big change in Earth. The temperatures began to cool down on the surface and the oceans. Temperatures were still around 150-200F, but were on a cooling trend. The earth’s crust was fully solid, and the earliest continents began to form.

Climate
Temperatures were around 150-200F, little change from the Hadean Eon. Volcanoes were everywhere, and they helped some of the temperatures go down.

Life
Oxygen began to appear around 3.4-3.5 billion years ago. This made way for the earliest of life, like eukaryota’s and other bacteria. Fossilized bacteria has been found in sedimentary and graphite rocks form around 2.9-3.4 billion years ago, which have the earliest fossils of life. They were found in Australia and North America.

The Archean Eon was to first to have official eras.